Are you able to use the Celestia scripts? I downloaded a ZIP file with images and the corresponding script, placed them in the same folder and run the script with Celestia 1.4.1 under MacOS X. But nothing happens.

Nice catch, Tman! Looks like clouds to me, rotating into view over the terminator. Judging by the timestamps this would make the original imagery upside-down. Here's an animated gif (click to enlarge):

To be honest, coding that particular bit was easy. I find providing a command line interface is more tedious and boring work. I'd still like to implement a better interpolation technique, something similiar to what digital cameras do.

Anyway, a couple of new takeouts, these have saturation kicked up. I don't know why the original images look so desaturated.

Kudos to the ESA and MEX teams! This is an exciting and inventive way to engage the public through existing hardware.

QUOTE (ugordan @ Aug 22 2008, 01:34 PM)

I'd still like to implement a better interpolation technique, something similiar to what digital cameras do.

Great work ugordan, it looks like you have these files well in hand. If you're looking for more advanced de-bayering, dcraw might be a good reference. It includes 3 different methods beyond bilinear. In terms of the color, do we know if there are any spec or calibration documents online? Pixel responsivity would be mighty helpful.

..placed them in the same folder and run the script with Celestia 1.4.1 under MacOS X. But nothing happens.

Paolo,

I think that the intention with the Celestia script is just to show where MEX was at the time that the image was taken. Reading from their website it says that this will help users determine what surface features are visible and the timing of the images available. While the images are available in a folder of the same name as the script, I don't see that they are related beyond that. Simply a way to compare the Mars Webcam images to a visualisation of the same region using Celestia.

I think that the intention with the Celestia script is just to show where MEX was at the time that the image was taken.

For each image, the script calls functions for selecting Mars and tracking it, which are supposed to bring the planet in the field of view. But I see only an empty star field. Also according to the script, the "M" and "N" should move to the next or previous image location, but this doesn't work. I don't see the instructions that the script should display, either.

Hmmm... I'd better check whether the version of Celestia I am using was compiled with support for the Lua language required by the VMC scripts.

A dodgy first version of the tool:vmc2rgb_v01.zip ( 37.97K )
Number of downloads: 423

It takes an input RAW file and writes out a PNG with the same filename and adds a "_rgb.png" suffix. For example:

CODE

VMC2RGB "08-183 12.23.52 VMC Img No 6.raw"

will produce "08-183 12.23.52 VMC Img No 6_rgb.png". Note that in windows command line prompt you need to use double quotes for filenames containing spaces such as these. The end qoute is not strictly necessary. If you associate the *.RAW file extension to the program (or if you just drag-n-drop the image on the program icon) you don't have to worry about this.

Also, the tool is dumb in that it will interpret any file you feed it as a 640x480 raw stream. I suppose I could make it grab PNGs as well sometime.

I'll consider adding an improved interpolation as slinted suggested later. I've done some reading and apparently the Bayer filter outputs have a fair amount of inter-channel "crosstalk" that causes saturation to go down which might explain the low saturation in these images. This is usually automatically handled by digital cameras with internal saturation boosting, in this particular case Photoshop's your friend.

These images remind me of the early Mariner pics of Mars: albedo features, maybe a mountain or two, with some craters thrown in. It's also interesting how the CCD has a Bayer filter, yet the main use of the camera did not require color capabilities.

Paolo, see if you can download Celestia 1.5.0. It runs the .cel script with no problems (perhaps a little slow to start, but then it hums along).

This did the trick, thanks. I upgraded to Celestia 1.5.1 and the VMC script worked. At first it didn't occur to me to try an upgrade because the script didn't mention dependence on any specific version of Celestia.

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